function cambiarestilo(){

  document.getElementById("css").href= "css/menu.css";
  document.getElementById("css1").href= "css/principal1.css";
  document.getElementById("css2").href= "css/reset.css";
  document.getElementById("css3").href= "css/slider.css";
   document.getElementById("content1").setAttribute("style","display:none");
    document.getElementById("content2").setAttribute("style","display:none");
	    document.getElementById("content4").setAttribute("style","display:none");
		 document.getElementById("content3").setAttribute("style","display:block");
		    document.getElementById("content5").setAttribute("style","display:none");

}
function cambiarestilo1(){

  document.getElementById("css").href= "css/box-properties.css";
  document.getElementById("css1").href= "principal22.css";
  document.getElementById("css2").href= "css/demo.css";
  document.getElementById("css3").href= "css/style3.css";
  

}